Interpretive Summary: Glycoalkaloids are secondary metabolites produced by potato plants, presumably for protection against phytopathogens such as bacteria, fungi, and viruses. We anticipate that glycoalkaloids may also exhibit antibiotic activities against human pathogens. In the present collaborative study carried out in Korea, we showed that glycoalkaloids isolated from five commercial potato varieties widely consumed in Korea and Japan also inhibit the growth of human cervical, liver, lymphoma, and stomach cancer cells and that mixtures of two glycoalkaloids can act synergistically in destroying the cells. This information can guide the development and use of health-promoting potatoes containing optimum combination of the two major glycoalkaloids a-chaconine and a-solanine.

Technical Abstract:
Methods were devised for the extraction, purification, isolation, and characterization of large amounts of pure a-chaconine and a-solanine from Dejima potatoes stored for two months at room temperature and for the extraction and analysis of total glycoalkaloids from five fresh potato varieties (Dejima, Jowon, Sumi, Toya, and Vora Valley). These compounds were then evaluated in experiments using a tetrazolium microculture (MTT) assay to assess the cell growth inhibitory activities of (a) the isolated pure glycoalkaloids separately, (b) artificial mixtures containing varying proportions of the two glycoalkaloids, and (c) the total glycoalkaloids isolated from each of the five potato varieties. All samples tested were found to inhibit the growth of the following human cancer cell lines: cervical (HeLa), liver (HegG2), lymphoma (U937), and stomach (AGS and KATO III) as well as normal human liver (Chang) cells. The results also show that (a) inhibitory activities of the pure glycoalkaloids were concentration dependent in the range 0.1 to 10 mg/mL; (b) a-chaconine was more active against the cancer cells than was a-solanine; (c) depending on the proportions of a-chaconine and a-solanine, some of the mixtures exhibited synergistic while others produced additive effects against the cells; and (d) the different cancer cells varied in their susceptibilities to the growth inhibition. The destruction of these cells was also observed by microscopy of untreated and glycoalkaloid-treated cancer cells. The possible significance of the results to food science and human health is discussed.